We propose to evaluate the effect of ventilatory muscle training on ventilatory muscle endurance and overall exercise performance in the elderly. In young subjects, peak exercise levels are reached at a point when maximal exercise minute ventilation is well below the maximal voluntary ventilation. The ventilatory reserve in the young is in excess of the requirements for maximal exercise. Ventilatory mechanics are not considered to be a limiting factor to exercise performance. With aging there are decreases in many pulmonary functions; most notable of these is the rapid decline in the maximal voluntary ventilation which decreases by 33% between the ages of 20-65 years. A drop of this magnitude markedly decreases the available ventilatory reserve and may, in fact, eliminate the ventilatory reserve for moderate endurance activity. This problem is potentially more prominent in two situations, 1) older women who live longer and who have smaller ventilatory capacities than men and 2) during arm work, as here the rise in exercise minute ventilation per unit increase in oxygen consumption is greater than during leg work. Ventilatory muscle training improves ventilatory muscle endurance. The application of this form of training to the elderly may provide them with increased ventilatory muscle endurance and this would potentially enable them to better perform steady-state leisure and work activities. Improved ventilatory muscle performance would then have important social and economic benefits in this ever enlarging population.